Red Angel's Trumpet
Your seeds should be planted when received for best results.
Getting started -- Soak your seeds for 10 minutes in a mixture of 1 part bleach to 10 parts water, then rinse and soak overnight in a cup of water.
Use small containers that have drainage holes, and fill with a well-draining medium, such as 2 parts sterilized potting soil to 1 part perlite. An alternate mix is equal parts of coir fiber and perlite, with some slow-release (pelleted) fertilizer added to the mix.
Fill the containers, place a seed in each pot, and cover with 1/2 inch (13 mm) of soil. Water the soil until evenly moist (but not soggy).
The best temperature for germination is between 64 to 74° F (18-23°). Nights cooler than this are ok. Avoid temperatures above 77° F (25°C) for prolonged periods. I recommend placing a minimum/maximum thermometer near the pots.
Until the seeds sprout, ensure that the soil surface does not dry out. If you place the pots in a plastic dome or bag to maintain moisture, leave it open slightly for some fresh air to enter.
Most of the seeds should start sprouting within 2-4 weeks, but some may take up to 2 months. Once they sprout, give them bright light, but shade them from strong afternoon sun.
Watering -- Aim to keep the soil evenly moist most of the time. Don't let the soil dry out completely, but also avoid keeping it water-logged. You can monitor the soil's moisture using a moisture meter probe, which are sold at garden shops and home improvement stores for about $5.
Fertilizing -- Like other Brugmansias, this one likes regular feeding. Feed about every 2 months with a slow-release (pelleted or organic) fertilizer. Cut back on the feedings if your plant goes through a period of slow growth, like during hot or cold temperatures.
It's normal for an older leaf to occasionally turn yellow and drop, but if it seems excessive, it's usually a sign of not enough nitrogen fertilizer. Or the soil may be too dry. If the new growth turns yellow with green veins, the pH of your soil or water is probably too high (alkaline). Try using a citrus fertilizer if this occurs.
Transplanting - When your seedlings are about 6-8 weeks old, repot to containers about a quart (1 liter) in size, and then on to 1-2 gallons (4-8 liters) a few months later.
Water the soil before repotting, to keep the soil ball from breaking apart, which can damage the roots. For the first week after repotting, give shade and no fertilizer.
Wait until your plants are 15 inches (35 cm) tall before planting them in the ground (in suitable climates). If you plan to keep them in containers indefinitely, the final size of the pot will depend on how large you let your plant grow. A full-size tree may need a very large pot! You may prune your plants to any size that is convenient.
Lighting -- Filtered sun or morning sun is best. Protect the plants from strong afternoon sun, especially in warm climates. They can take full sun in cool climates like coastal California, but they will need more fertilizer and water.
Climate -- This plant comes from higher elevations than typical Brugmansias, so it used to mild daytime temperatures, and nights that are cool. Temperatures above the low 70s (23°C) can inhibit flowering, and the plant might decline if temperatures are consistently above 85° F (30°C), especially if nights are warm.
It can survive brief dips down to 26-28° F (-2 to -3°C), but it's best to protect it from frost.
Over about 40% humidity is best. Indoors, if your humidity drops below this, consider using an ultrasonic room humidifier, which are sold at home improvement stores and thrift shops.
Pruning & shaping -- You may prune your plants to any shape you wish. Avoid removing too many branches at one time.
Bugs to watch for -- Whitefly, spider mites (tiny "dots" under the leaves), aphids (green ones are hard to see), snails/slugs.
If you have any questions or problems, feel free to email me.
Good luck with them!
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